<?xml version="1.0" encoding="UTF-8"?>
<doctype>
  <enumGroup name="asia">
    <enum>JP</enum>
    <enum>TH</enum>
  </enumGroup>
  <enumGroup name="europe">
    <enum>UK</enum>
    <enum>FR</enum>
    <enum>IT</enum>
  </enumGroup>
  <enumGroup name="world">
    <enumGroupRef name="asia"/>
    <enumGroupRef name="europe"/>
  </enumGroup>
  <element>
    <name>employee</name>
    <pcdata/>
  </element>
  <attlist>
    <name>employee</name>
    <attribute>
      <name>country</name>
      <tokenized>
        <enumGroupRef name="world"/>
      </tokenized>
      <implied/>
    </attribute>
  </attlist>
</doctype>